Sweden’s King Carl XVI Gustaf celebrated his golden jubilee on Friday, marking 50 years since he ascended the throne on Sept. 15, 1973. He is the longest-reigning king in the history of the Swedish monarchy, which stretches back more than 1,000 years. The Roman numeral XVI might seem to indicated he's the 16th king named Carl, but that's not the case. In Sweden, mythical kings have been added to the list. Nowadays, the king's duties are only ceremonial, and while queens have been rare in the past — expect more gender balance in the future. The succession rules were c...